An integrated circuit (IC) is formed by creating one or more devices (e.g., circuit components) on a semiconductor substrate. Each device is separated from the other devices using an isolation feature such as a shallow trench isolation (STI) structure. However, some devices have detrimental narrow channel width effects, such as different threshold voltage (Vt) behavior with different gate width devices. This is because the oxygen (O) elements in shallow trench isolation (STI) oxide materials can diffuse into the gate stack and influence the Vt of the CMOS or other device. This phenomenon leads to perplexity for an IC designer to design a circuit with different dimension devices.
As such, there is a need for a narrow channel width effect modification in a shallow trench isolation (STI) device.